Bug 23883 – `#line` is off by one and off by two if a line comment follows

```d #line 3 "a.d" ``` and ```d #line 3 "a.d" // ``` behave differently: In the first case, the #line is line 2, in the second case, the #line is line 1. I created https://github.com/dlang/dlang.org/pull/3601 to document the current behavior in the non-comment case.

The #line directive needs to be terminated by a newline or EOF. In your example the newline is commented, therefore whatever comes next after the comment on the exact following line has to be a newline or EOF so that the directive is correctly lexed. I think that the best way to proceed here is to add a spec mention about this as fixing will add unnecessary complexity (checking for comments before the directive ends) to support an unlikely corner case.

So, you’re suggesting that we make a bug a feature. Checking for comments before the directive ends isn’t that big of a deal. You don’t even have to handle it correctly, you can make it an error if that is easier. It’s surprising, and you shouldn’t surprise users.

(In reply to Bolpat from comment #2) > So, you’re suggesting that we make a bug a feature. Checking for comments > before the directive ends isn’t that big of a deal. > No, I am saying that this is such niche case (why would you attach comments to line directives?) that it doesn't really warrant the complexity added in the lexer. But I understand your point of view, that's why I'm leaving this bug report open. > You don’t even have to handle it correctly, you can make it an error if that > is easier. It’s surprising, and you shouldn’t surprise users.

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